1. Field of the Invention
The present invention relates to electrodeposition such as is practiced in the automotive industry.
2. Description of the Art Practices
Electrodeposition is defined as the process of depositing a film forming material through the use of electrical potential. There are two forms of electrodeposition. The first and most widely known and used form is that of anodic deposition wherein the negatively charged film forming material is attracted to the anode where the negative charge is removed and the material is plated out. The second form of electrodeposition is known as cationic deposition wherein the film forming material contains a positively charged group which is attracted to the cathode. At the cathode the positive charge of the film forming material is neutralized by the electrons flowing through the cathode and the film is deposited thereon. In either cathodic or anodic electrodeposition of course, the substrate to which the film is applied was the electrode involved in the reaction. A second cure, usually thermal, is employed to fix the film forming material onto the desired surface.
Considerable discussion of the subject of both cationic and anodic electrodeposition is found in THE CHEMISTRY OF BINDERS FOR ELECTRODEPOSITION found in PROGRESS IN ORGANIC COATINGS, 7 (1979) Pages 1-77. Specific systems which discuss cationic electrodeposition are found in U.S. Pat. No. 3,922,253 issued Nov. 25, 1975 to Jerabek et al.
It is known in the art that acrylic containing compounds may be utilized to finally cure a film-forming substance into a resin through the use of radiation or photoinitiation techniques. It is also known that acrylic compounds may be used as prepolymers in the film-forming system by reacting the acrylic or methacrylic group with a second reactive compound such as an amine and thereafter utilizing the additional functionality on the amine compound to finally cure the resin system.
Among the art which describes the various techniques and uses of acrylic or methacrylic compounds in resin systems are U.S. Pat. No. 3,127,365 issued Mar. 31, 1964 to Floyd wherein amino-polyamide compounds which have been modified with acrylic compounds are discussed. In U.S. Pat. No. 3,558,387 issued Jan. 26, 1971 to Bassemir et al. certain photopolymerizable compositions and specific photoinitiators are discussed. U.S. Pat. No. 3,637,618 issued Jan. 25, 1972 to May sets forth curable polyester compositions containing acrylic functionalities in the backbone of the polyester.
Laudise in U.S. Pat. No. 3,816,366 issued June 11, 1974 describes adducts of active acrylic compounds and an aminoamide which is suitable as a curing agent for epoxies in aqueous systems. U.S. Pat. No. 3,844,916 issued Oct. 29, 1974 to Gaske describes radiation curable Michael addition reaction products obtained by reacting an amine with a stoichiometric excess of a polyacrylate. Borden et al. in U.S. Pat. No. 3,876,518 issued Apr. 8, 1975 describes the reaction products of organic amines, acrylic substances and epoxidized soybean oil. The compositions of Borden et al. are stated to be useful either alone or in conjunction with a photosensitizer for use as inks or coatings. Other disclosures of compounds containing polyacrylate esters are found in U.S. Pat. No. 4,051,195 to McWhorter issued Sept. 27, 1977 wherein the reaction products of epoxide resin and a polyacrylate or polymethacrylate ester are described.
U.S. Pat. No. 3,446,723 to Pohlemann et al. issued May 27, 1969 describes cationic coating compositions containing acrylic or methacrylic acid aminoalkylamide compounds. Dowbenko in U.S. Pat. No. 3,679,564 issued July 25, 1972 describes imine-modified carboxylic acid containing acrylic resins as being useful in cationic deposition. U.S. Pat. No. 3,853,803 issued to Anderson et al. on Dec. 10, 1974 describes cationic compounds useful for electrodeposition containing carboxylated acrylic copolymers. Throughout this patent percentages and ratios are by weight and temperatures in Celsius unless otherwise indicated.